The new prefect of the Congregation for the Doctrine of the Faith has re-stated that the acceptance of the Second Vatican Council is a prerequisite for the traditionalist Society of St. Pius X to rejoin the Church.

“One can only be Catholic if one fully recognizes the faith of the Church. This includes the Second Vatican Council, which is a particularly important teaching,” Bishop Gerhard Ludwig Muller said to Vatican Radio July 4 in his first and only interview since taking up his new post.

“It is therefore important to overcome internal blockages – groups on the fringes – and that one simply has to trust our Holy Father Benedict XVI and all those that who surround him,” he remarked.

In September 2011 Bishop Muller’s predecessor, American Cardinal William J. Levada, presented the Society with a “doctrinal preamble” setting out what they would have to agree with in order to heal its 24-year rift with Rome.

Although the document was never made public, it is widely thought to include the acceptance of the Second Vatican Council as a key condition. Discussions between both sides are still ongoing.

Bishop Muller, 64, was appointed to his new post July 2, having previously been Bishop of Regensburg in Germany for 10 years.

“I feel like a first-grader in school. A lot of things are new for me,” he admitted, even though he was already familiar with the congregation’s work, having been a member for five years. “Despite that,” he added, “it is a big change from being a local bishop to a bishop at the Roman Curia.”

The office he now holds within the Curia puts him in charge of one of the oldest and most significant Vatican departments. The congregation has its roots in the 16th century counter-Reformation when it went by the grand title of the Supreme Sacred Congregation of the Roman and Universal Inquisition. In 1908 it was restyled the Supreme Sacred Congregation of the Holy Office. It was renamed again with its present title in 1965 by Pope Paul VI.

Bishop Muller said the primary job of his new department is “promoting the Catholic faith” in “a positive way,” since “faith is something that heals.”

“A lot of Catholics do not know, unfortunately, what is really the content of our faith and so let themselves maybe also go against the Church, while they believe in something which is false,” he said.

A personal friend of Pope Benedict XVI, the two men have a background in academia, with Bishop Muller specializing in dogmatic theology. He also has a long track record in promoting ecumenical relations particularly with the Russian Orthodox Church and Lutherans.

“Ecumenical doesn't mean that one must give up one's own belief, rather, that we give our Catholic understanding in a way that it is understood from other sides,” he said.

“That's why we hope that the ecumenical process continues and that God gives us the grace that all Christians come united in one Church.”